body, html {
  width: 100%;
  height: 100%;
  font-size: 15px;
  font-family: "微软雅黑"
}

@media all and (max-width: 320px)  {
  html, body {
    font-size: 12px; 
  }
}

@media (min-width: 321px) and (max-width: 375px)  {
  html, body {
    font-size: 13px; 
  }
}
 // 1px = 0.06rem  1px = 1/15rem